source: lib/format_atmhdr.c

/*
 *
 * Copyright (c) 2007-2016 The University of Waikato, Hamilton, New Zealand.
 * All rights reserved.
 *
 * This file is part of libtrace.
 *
 * This code has been developed by the University of Waikato WAND
 * research group. For further information please see http://www.wand.net.nz/
 *
 * libtrace is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * libtrace is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *
 */
#define _GNU_SOURCE

#include "config.h"
#include "common.h"
#include "libtrace.h"
#include "libtrace_int.h"
#include "format_helper.h"
#include "wandio.h"

#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

/* This particular format covers the ATM cell header capture format used to
 * take the Auckland VII trace set.
 *
 * Each capture record contains only a timestamp and the first four bytes of 
 * the ATM header - nothing else. 
 *
 * As a result, there isn't a lot you can actually do with these traces!
 *
 * Libtrace does not support writing using this format, because it is so
 * useless :)
 */

/* Returns the size of the ATM cell framing header */
static int atmhdr_get_framing_length(const libtrace_packet_t *packet UNUSED)
{
        return sizeof(atmhdr_t);
}

/* Initialise an input trace to read an ATM cell header capture */
static int atmhdr_init_input(libtrace_t *libtrace) {
        libtrace->format_data = NULL; /* No format data needed */
        return 0;
}

/* Start an ATM cell header input trace */
static int atmhdr_start_input(libtrace_t *libtrace)
{
        if (libtrace->io) /* Already open? */
                return 0;
        libtrace->io = trace_open_file(libtrace);
        if (libtrace->io)
                return 0;
        return -1;
}

/* Close an ATM cell header input trace */
static int atmhdr_fin_input(libtrace_t *libtrace)
{
        wandio_destroy(libtrace->io);
        return 0;
}


/* Converts a buffer containing a recently read ATM cell header record into
 * a libtrace packet */
static int atmhdr_prepare_packet(libtrace_t *libtrace, 
                libtrace_packet_t *packet, void *buffer, 
                libtrace_rt_types_t rt_type, uint32_t flags) {

        /* If the packet previously owned a buffer that was not the buffer
         * containing the new packet data, we need to free the old one to 
         * avoid leaking memory */
        if (packet->buffer != buffer &&
                        packet->buf_control == TRACE_CTRL_PACKET) {
                free(packet->buffer);
        }

        /* Set the buffer owner appropriately */
        if ((flags & TRACE_PREP_OWN_BUFFER) == TRACE_PREP_OWN_BUFFER) {
                packet->buf_control = TRACE_CTRL_PACKET;
        } else
                packet->buf_control = TRACE_CTRL_EXTERNAL;

        /* Update the packet pointers appropriately */
        packet->buffer = buffer;
        packet->header = buffer;
        packet->payload = (void*)((char*)packet->buffer + 
                        libtrace->format->get_framing_length(packet));

        /* Set the packet type */
        packet->type = rt_type;

        return 0;
}

/* Reads the next ATM cell header record from the given trace and writes it
 * into a libtrace packet */
static int atmhdr_read_packet(libtrace_t *libtrace, libtrace_packet_t *packet) {
        int numbytes;
        void *buffer;
        uint32_t flags = 0;
        
        /* Make sure we have a buffer available to read the next record into */
        if (!packet->buffer || packet->buf_control == TRACE_CTRL_EXTERNAL) {
                packet->buffer=malloc((size_t)LIBTRACE_PACKET_BUFSIZE);
        }
        buffer = packet->buffer;
        flags |= TRACE_PREP_OWN_BUFFER;
        
        packet->type = TRACE_RT_DATA_ATMHDR;

        /* The records are a fixed size so we can read the entire record in
         * one go */
        if ((numbytes=wandio_read(libtrace->io, buffer, (size_t)12)) != 12)
        {
                if (numbytes != 0) {
                        trace_set_err(libtrace,TRACE_ERR_WANDIO_FAILED,"read(%s)",libtrace->uridata);
                }
                return numbytes;
        }

        /* Update all our packet pointers appropriately */
        if (atmhdr_prepare_packet(libtrace, packet, buffer, 
                                TRACE_RT_DATA_ATMHDR, flags)) {
                return -1;
        }
                                
        
        return 12;
}

/* Get the link type for an ATM cell header record */
static libtrace_linktype_t atmhdr_get_link_type(const libtrace_packet_t *packet UNUSED) {
        /* Unsurprisingly, we're always going to be an ATM header */
        return TRACE_TYPE_ATM;
}

/* Get the capture length for an ATM cell header record */
static int atmhdr_get_capture_length(const libtrace_packet_t *packet UNUSED) {
        /* There is always 4 bytes of ATM header retained by this format */
        return 4;
}

/* Get the wire length for an ATM cell header record */
static int atmhdr_get_wire_length(const libtrace_packet_t *packet UNUSED) {
        /* ATM packets are 53 byte fixed length records */
        return 53;
}

/* Returns the timestamp for an ATM cell header record in the ERF timestamp
 * format */
static uint64_t atmhdr_get_erf_timestamp(const libtrace_packet_t *packet) {
        uint64_t ts;
        atmhdr_t *atm = (atmhdr_t *)packet->header;
        
        /* Basically, the capture format header is an ERF timestamp except
         * the two 32-bit segments are reversed */
        ts = (uint64_t)atm->ts_fraction + ((uint64_t)atm->ts_sec << 32);

        return ts;
}

static struct libtrace_format_t atmhdr = {
        "atmhdr",
        "$Id$",
        TRACE_FORMAT_ATMHDR,
        NULL,                           /* probe filename */
        NULL,                           /* probe magic */
        atmhdr_init_input,              /* init_input */
        NULL,                           /* config_input */
        atmhdr_start_input,             /* start_input */
        NULL,                           /* pause_input */
        NULL,                           /* init_output */
        NULL,                           /* config_output */
        NULL,                           /* start_output */
        atmhdr_fin_input,               /* fin_input */
        NULL,                           /* fin_output */
        atmhdr_read_packet,             /* read_packet */
        atmhdr_prepare_packet,          /* prepare_packet */
        NULL,                           /* fin_packet */
        NULL,                           /* write_packet */
        NULL,                           /* flush_output */
        atmhdr_get_link_type,           /* get_link_type */
        NULL,                           /* get_direction */
        NULL,                           /* set_direction */
        atmhdr_get_erf_timestamp,       /* get_erf_timestamp */
        NULL,                           /* get_timeval */
        NULL,                           /* get_timespec */
        NULL,                           /* get_seconds */
        NULL,                           /* get_meta_section */
        NULL,                           /* seek_erf */
        NULL,                           /* seek_timeval */
        NULL,                           /* seek_seconds */
        atmhdr_get_capture_length,      /* get_capture_length */
        atmhdr_get_wire_length,         /* get_wire_length */
        atmhdr_get_framing_length,      /* get_framing_length */
        NULL,                           /* set_capture_length */
        NULL,                           /* get_received_packets */
        NULL,                           /* get_filtered_packets */
        NULL,                           /* get_dropped_packets */
        NULL,                           /* get_statistics */
        NULL,                           /* get_fd */
        trace_event_trace,              /* trace_event */
        NULL,                           /* help */
        NULL,                            /* next pointer */
        NON_PARALLEL(false)
};
        

void atmhdr_constructor(void) {
        register_format(&atmhdr);
}